Recently, energy storage system (ESS) gathers growing attentions as one of the devices to implement the smart grid by considering consumption pattern (time and place of use) of electrical power users. In this case, the energy storage system plays a crucial role for enhancing efficiency of the electrical power management, such as, establishing a bidirectional power supply system, ensuring flexibility of a power transmission and distribution system, preventing blackout, and so on, because it enables storage of the idle power in terms of each of power generation, transmission and distribution, and electrical power consumer.
Accordingly, by using the ESS, the electrical power user may store the idle power during nighttime, and use the stored power during daytime. For the above, because the ESS is provided with the pouch-shaped secondary batteries within a battery pack, the secondary batteries are required by the electrical power user to have high output and high capacity throughout the repeated charging and discharging in the ESS.
However, such demand for high output and high capacity incidentally leads to heat generation from the secondary batteries, which is resulted from the electrochemical reaction of the components within the secondary batteries during repeated charging and discharging of the secondary batteries. This heat generation of the secondary batteries causes heat accumulation in the secondary batteries, deteriorating operation of the secondary battery. The deteriorated operation of the secondary battery shortens a service life of the ESS.
In order to minimize the heat accumulation in the secondary battery, Korean Patent Application No. 10-2009-0000302, published on Jan. 7, 2009, discloses a ‘Large and medium battery pack having excellent cooling efficiency.’ For cooling the secondary batteries, the large and medium battery pack is configured such that refrigerant (air) is introduced into an upper end of one side of a front surface, flowed in a vertically-downward direction between battery modules (including the secondary batteries), and then flowed out of a lower end of the one side of the front surface. That is, because a refrigerant passage is formed to be in a U shape within the large and medium battery pack, the large and medium battery pack needs a lengthy time to cool the secondary batteries, due to the refrigerant passage being longer than a length of the large and medium battery pack itself.
Further, Korean Patent Application No. 10-2009-0000313, published on Jan. 7, 2009, discloses a large and medium battery pack with enhanced cooling efficiency. The large and medium battery pack with enhanced cooling efficiency is configured such that, for cooling the secondary batteries, the refrigerant (air) is introduced into an upper end of a rear surface, flowed in a vertically-downward direction between module assemblies (including the secondary batteries), and continue to be flowed out of a lower end of a front surface. That is, because the refrigerant passage is formed as a part of a gammadion character shape ‘’ within the large and medium battery pack, the large and medium battery pack needs a long time for cooling the secondary batteries because it locally confines hot air therewithin.
Referring to the related art described above, the ESS shows a configuration which is difficult to expeditiously cool the secondary batteries in the battery pack (hereinbelow, ‘batteries’) within a short time.